Hydrofluorocarbon compositions

ABSTRACT

A composition which comprises 1,1,1,3,3-pentafluorobutane (HFC-365mfc) and 1,1,1,3,3-pentafluoropropane (HFC-245fa) in a weight ratio HFC-365mfc/HFC-245fa of from 60:40 to 75:25.

The present invention relates to compositions of1,1,1,3,3-pentafluorobutane (HFC-365mfc) and1,1,1,3,3-pentafluoropropane (HFC-245fa), which are useful as blowingagents for polymer foams.

Mixtures HFC-365mfc and HFC-245fa are suitable in particular for themanufacture of polyurethane foams and modified polyurethane foams suchas polyisocyanurate foams. U.S. Pat. No. 6,080,799 discloses inter aliaa blowing agent mixture of HFC-365mfc/HFC-245fa.

It has been discovered that in certain formulated systems forpolyurethanes containing polyols and mixtures of HFC-365mfc andHFC-245fa, a flash point may be observed in spite of the nonflammablenature of the polyols and of the mixtures of HFC-365mfc and HFC-245farespectively.

It was desirable to find a blowing agent composition which does notdisplay a flash point when used in fully formulated systems and whichallows for manufacture of foams which display good insulation propertiesover a wide temperature range.

Consequently, the invention concerns a composition which comprises1,1,1,3,3 -pentafluorobutane (HFC-365mfc) and1,1,1,3,3-pentafluoropropane (HFC-245fa) in a weight ratioHFC-365mfc/HFC-245fa of from 60:40 to 75:25.

It has been found, surprisingly, that the compositions according to theinvention allow for safe manufacture of (modified) polyurethane foamswith fully formulated systems having no flash point whereas obtainedclosed-cell foams are particularly suitable for thermal insulation atlow temperatures, as condensation of the cell gas can be substantiallyavoided.

Polyurethane is understood to mean the polymers resulting essentiallyfrom the reaction of polyols and of isocyanates. These polymers aretypically obtained from formulations exhibiting an isocyanate numberfrom 100 to 180. Modified polyurethane is understood to mean thepolymers resulting from the reaction of polyols and of isocyanates whichcontain in addition to urethane functional groups, other types offunctional groups, in particular triisocyanuric rings formed bytrimerization of isocyanates. These modified polyurethanes are normallyknown as polyisocyanurates. These polymers are typically obtained fromformulations exhibiting an isocyanate number from 180 to 550.

In the composition according to the invention, the weight ratioHFC-365mfc/HFC-245fa is greater than or equal to 60:40. Often the weightratio HFC-365mfc/HFC-245fa is greater than or equal to 65:35.Preferably, the weight ratio HFC-365mfc/HFC-245fa is greater than orequal to 67:33. A weight ratio HFC-365mfc/HFC-245fa of about 70:30 isparticularly preferred.

In the composition according to the invention, the weight ratioHFC-365mfc/HFC-245fa is lower than or equal to 75:25. Often the weightratio HFC-365mfc/HFC-245fa is lower than or equal to 73:27. Preferably,the weight ratio HFC-365mfc/HFC-245fa is lower than or equal to 72:28.

The compositions according to the invention which consist essentially ofHFC-365mfc and HFC-245fa are particularly preferred.

The invention concerns also a premix intended for the preparation ofpolyurethane or modified polyurethane foams comprising

a) at least one polyolb) a catalyst for the reaction of isocyanates with polyolsc) a composition according to the invention

For the purposes of the present invention, premix is understood to meanany composition comprising at least one polyol, at least one blowingagent and at least one catalyst.

Surprisingly, the compositions according to the invention are chemicallystable in the premix. Consequently, the latter can optionally beformulated without a stabilizer against the potential degradation of thecomposition according to the invention.

For the purposes of the present invention, polyol is understood to meanany compound containing at least two functional groups which react withisocyanates. These functional groups contain at least one activehydrogen atom, such as defined by the Zerewittinoff reaction. The activehydrogen atom is generally a hydrogen atom bonded to an oxygen, nitrogenor sulphur atom. Any polyol conventionally used to prepare polyurethanefoams can be used in the premixes according to the invention. Mentionmay in particular be made of polyether polyols and polyester polyols.

The catalyst of the premixes according to the invention comprises acompound with catalyses the formation of the —NH—CO—O— urethane bond byreaction between a polyol and an isocyanate or which activates thereaction between an isocyanate and water, such as tertiary amines andorganic tin, iron, mercury or lead compounds. Mention may in particularby made, as tertiary amines, of triethylamine,N,N-dimethylcyclohexylamine (DMCHA), N-methylmorpholine (NMM),N-ethylmorpholine, dimethylethanolamine, diaza[2.2.2]bicyclooctane(triethylenediamine) and substituted benzylamines, such asN,N-dimethylbenzylamine (DB). Mention may in particular be made, asorganic tin or lead compounds, of dibutyltin dilaurate, stannousoctanoate and lead octanoate.

The catalyst of the premixes according to the invention can, inparticular when the latter are intended for the manufacture of modifiedpolyurethane (polyisocyanurate) foams, comprise a compound whichcatalyses the trimerization of isocyanates to triisocyanurates.Compounds which catalyse the trimerization of isocyanates which can beused in the premixes according to the invention are in particulartriazines.

In addition to the polyol, the composition according to the inventionand the catalyst, the premixes according to the invention canadditionally contain various additives commonly used to preparepolyurethane or modified polyurethane foams, such as, in particular,water, surface-active agents, antioxidizing agents, flame-retardantagents and/or pigments. The more particularly preferred premixesaccording to the invention are essentially composed of at least onepolyol, the composition according to the invention, at least onecatalyst which promotes the polyol/isocyanate reaction and at least oneof the usual additives mentioned above.

The proportions of polyol, catalyst, the composition according to theinvention and optional additives in the premixes according to theinvention vary, in particular according to the application, the type offoam prepared, the nature of the polyol and the nature of the catalyst.

In practice, the amount of catalyst used generally varies fromapproximately 0.050 to 10 parts by weight per 100 parts by weight ofpolyol. In general, the amount of the composition according to theinvention is from 1 to 80 parts by weight per 100 parts by weight ofpolyol. It is preferably from 10 to 60 parts by weight per 100 parts byweight of polyol. The amounts of water, surface-active agents,plasticizing agents and/or flame-retardant agents are thoseconventionally used to prepare polyurethane or modified polyurethanefoams.

The invention also relates to a process for the manufacture ofpolyurethane or modified polyurethane foams, in which at least oneisocyanate is reacted with at least one polyol in the presence of thecomposition according to the invention, of at least one catalyst and,optionally, of other usual additives.

Any isocyanate conventionally used to manufacture such foams can be usedin the process according to the invention. Mention may be made, by wayof example, of aliphatic isocyanates, such as hexamethylenediisocyanate, and aromatic isocyanates, such as tolylene diisocyanate ordiphenylmethane diisocyanate.

Generally, the process according to the invention is carried out in thepresence of water. In this case the amount of water used is preferablyequal to or greater than 1 part by weight per 100 parts of polyol. Morepreferably, the amount of water used equal to or greater than 1.5 partsby weight per 100 parts of polyol.

In this case the amount of water used is preferably equal to or lessthan 2.5 parts by weight per 100 parts of polyol. More preferably, theamount of water used equal to or less than 2 parts by weight per 100parts of polyol.

In the process according to the invention, the composition according tothe invention can be supplied to the reaction in the form of the premixaccording to the invention. The composition according to the inventioncan also be supplied to the reaction in the form of a mixture of thecomposition with the isocyanate.

The invention concerns also a polyurethane or modified polyurethane foamwhich is obtainable according to the process according to the invention.The polyurethane or modified polyurethane foam according to theinvention is preferably a rigid closed-cell foam. The polyurethane ormodified polyurethane foam can also be selected from a flexible orsemi-flexible foam, an integral skin foam and a monocomponent foam.

The invention concerns also a thermal insulation material, whichcomprises a polyurethane or modified polyurethane foam according to theinvention.

Specific examples of thermal insulation material according to theinvention include insulation panels, tubes for pipe insulation, sandwichpanels, laminates and block foams.

The thermal insulation material according to the invention generallysubstantially keeps its insulating properties when used in contact withan atmosphere having a temperature of 10° C. or lower. Often thetemperature of use can be 5° C. or lower. The temperature can even be 0°C. or lower without substantial condensation. The thermal insulationmaterial according to the invention is particularly suitable when usedin contact with an atmosphere having a temperature of −10° C. or higher.

The examples here after are intended to illustrate the invention in anon-limitative manner.

EXAMPLE 1 PUR Manufacture with a 70:30 Composition of HFC-365mfc andHFC-245 fa

A preparation of HFC-365mfc/HFC-245fa in a ratio 70:30 starts boiling at27° C. 100 g Polyol-composition of an aromatic Polyesterpolyol and anaromatic Polyetherolyol with an OH number of 450 and 15 gTris-Chioroisopropylphosphate as a flame retardant, 2 gMimethylcyclohexylamine as a catalyst and 1.5 g of aSiloxanepolyalkeneoxide-Copolymer as a stabilizer, 2 g of water and 20 gof HFC-365mfc/HFC-245fa in a ratio 70:30 were blended and then mixedwith 130 g of 4,4-Diisocyanatediphenylmethane. A rigid foam was obtainedwith a density of 35 kg/m³.

EXAMPLE 2 PUR Manufacture with a 75:25 Composition ofHFC-365mfc/HFC-245fa

Example 1 was repeated with 20 g of HFC-365mfc/HFC-245fa in a ratio75:25 having a boiling start of 28° C. The density was the same as inExample 1.

EXAMPLE 3

Example 1 was repeated, adding the blowing agent composition separately,at first 14 g HFC-365mfc and then 6 g of HFC-245fa, using a dip tube. Arigid foam was obtained with a density of 35 kg/m³.

The compositions do not present any flash point when used in a premixwith polyols.

1-10. (canceled)
 11. A composition which consists of1,1,1,3,3-pentafluorobutane (HFC-365mfc) and1,1,1,3,3-pentafluoropropane (HFC-245fa) in a weight ratioHFC-365mfc/HFC-245fa of from 60:40 to 73:27.
 12. The compositionaccording to claim 11, wherein the weight ratio HFC-365mfc/HFC-245fa isfrom 65:35 to 73:27.
 13. The composition according to claim 11, whereinthe weight ratio HFC-365mfc/HFC-245fa is from 67:33 to 72:28.
 14. Thecomposition according to claim 12, wherein the weight ratioHFC-365mfc/HFC-245fa is about 70:30.
 15. A premix intended for thepreparation of polyurethane or modified polyurethane foams comprising a)at least one polyol b) a catalyst for the reaction of isocyanates withpolyols c) a composition according to claim
 12. 16. A process for themanufacture of polyurethane or modified polyurethane foams in which atleast one isocyanate is reacted with at least one polyol in the presenceof at least one catalyst and in the presence of the compositionaccording to claim
 12. 17. A polyurethane or modified polyurethane foamwhich is obtainable according to the process of claim
 16. 18. Thepolyurethane or modified polyurethane foam according to claim 17, whichis a rigid closed cell foam.
 19. A thermal insulation material, whichcomprises a polyurethane or modified polyurethane foam according toclaim
 17. 20. A thermal insulation material, which comprises thepolyurethane or modified polyurethane foam according to claim
 18. 21. Acomposition which consists of 1,1,1,3,3-pentafluorobutane (HFC-365mfc)and 1,1,1,3,3-pentafluoropropane (HFC-245fa) in a weight ratioHFC-365mfc/HFC-245fa of from 60:40 to 65:35.
 22. The compositionaccording to claim 21, wherein the weight ratio HFC-365mfc/HFC-245fa is60:40.
 23. A premix intended for the preparation of polyurethane ormodified polyurethane foams comprising a) at least one polyol b) acatalyst for the reaction of isocyanates with polyols c) a compositionaccording to claim
 21. 24. A process for the manufacture of polyurethaneor modified polyurethane foams in which at least one isocyanate isreacted with at least one polyol in the presence of at least onecatalyst and in the presence of the composition according to claim 21.25. A polyurethane or modified polyurethane foam which is obtainableaccording to the process of claim
 24. 26. The polyurethane or modifiedpolyurethane foam according to claim 25, which is a rigid closed cellfoam.
 27. A thermal insulation material, which comprises a polyurethaneor modified polyurethane foam according to claim
 25. 28. A thermalinsulation material, which comprises the polyurethane or modifiedpolyurethane foam according to claim
 26. 29. The composition as claimedin claim 12, wherein the composition when used in a premix with polyolsdoes not present a flash point.